Field-sensitive hydraulic apparatus



Sept. 8, '1953 F. PIERCE 2,651,258

FIELD SENSITIVE HYDRAULIQ APPARATUS "Filed sept. 1o, 1948' 4+# JNVE'NTOR. F/RTH P/ERCE ArroRA/EV Patented Sept. 8, 1953 UNITED; itsI PATENT (Granted: underv Title 35, U,Y S@ Gode 5f (1952.),

sec. 266% Thisuinyentionfrelates to hydraulicf apparatus, andi. more particu-larlyr to: hydraulicA apparatus and# systems employ-inght a. fluid-f which is L sensitivectof'elds such" as-an electro -m-agnetic :fieldu It isranf object ofith-is'iin-ven-tion to provide 'hydlfaulic-I .apparatus v:employing: eld- 'sensitive 1 flu-id toofacililtate the control-i andi mover-nenty of the fluidi in l the hydraulic system.

Itl isfY a-nothen object s* of this invention to providesparticularhydraulic devices for usein a hydraulic system `employing eld-sensitive-uids suchi. aseaiferroemagneticfluid, i. e. a fluidexhibitingo ferro-magnetic.- properties.Y

Itfislanotherfobject of lthisfinvention` to simplify thacontrolfandfmovement. of==fluid-in a hydraulic. system.

It is a further.,objeciroLthisrinvention to control the flow and movement of uid in a hydraulic ysystem Without the use oil movi-ng4A parts.

Itislan'additionalobject oflthislinvention to provide controlI off'iluid-iin ahydraulic system continuously: variable-,l non-discrete increments, without: the. employment of *anyv moving parts..

ItLisLa,- particular-objectA of this invention to Dlfoyide-avalye forvthescontrol of iield-sensitive fluidaina,;nydraulic1 system, particularlyv ina closedihydrauli'c.` system.`

Itris another particular object of this-invention' to.: provide a pumping.A of as field-sensitivel fluid;

It isf afurtheraparticularfobject offthis invention -to.:.p1 'o.videfv a.:.pump; the. capacity ofV whichmayrf be continuously varied without the' employmentz of: anyfmoyablefcontrol parts in the Dl'lmDJ-A.

Other.` obiectsand manyv ofv the attendant. ad- Vantages:ofrthisinvention Will be readily lappreciatedfasfthe: same .becomes better-understood by I eferenceftor the lfollowingdescription.

\ Imaccordance with. the instant inventionthe hydl'allli'cfV apparatus comprises Y. a conduitf systempreferably a closed; system, lledf with a: ield-sensitiye-i fluid;v such as. a ferro-magnetic uidpgil; er; la;liuic:1;ha-ving--ferrofmagnetic, proper tiesr, Suclfiigaxuidj'changes its. viscosityl under@ the; influence; of at.; lield Whenz the; iiuidt is aw ferrofmagnetic.; fluidi the: viscosityae increases: markedly; in;asmagnetic;r` -field t andpif theAv walls. ofther conduitfsystemare; of ferromagnetic` ma? terial, the -uid tends;toadhere Inpperation,` Such. a'closed-.Condult system ssllbev jected to a field (in appropriate casesga;mag;.l neticl field) which alters-theflowCharacteristics Otfthe-Q fluid .and-.thereby leads toiacoptiriuously variable and easily applied means for controlpun'ip'especiallyv designed forl the o Exemplary of suclfi hydraulic apparatus ar valvelforieldesensitive fluid, the basicelements of.:-` whichu include abody. having.v passage Ynreansi for fthefowofiiuid through the valve, and lmeansi` for; establishing a viield .in the: passage` meansr-A to: therebyI control thel flow.; of the=- eldlsensitivef fluid .through .the bodyfof: the .valira-'1. Wh'em the; uid is, a ferro-magneticfuid; theabod'y prefere. ably f includes an electrical winding.E vmhichlisi-Lets,y fecltive. to.create, amagneticneldiin the passages. and thereby markedly., increase the:L viscosityifof thauidin the valve passage,4 tothe pointawherea completely@ blockeda org; pref erab1-y,- mayA bei; merely@ impeded-.z tot desired degree.

A; further example; off' such-1 hydraulica-v apparatusf` is a pump: for; field-sensitive; iluid;.thef pumping-,capacity;v of which" mayfgbe;readilyf;cori:1 trolled; byf; controllingthe` field-1. strengthzanpliedzi; by.: the pump-tothe fluid.; Innthefpreierred case.; of.; a; ferrofmagnetic fluid. the-1 p umprincludes am electrical winding,Y the fgeneratedf iielchv strenabh ofi` Which-l mayffbe, varied@ by sirnplyf varying, thef' rotor;I v v v a. means, so that-ftheaferro magnetic-huid;adheres; tothe.ipumpgrotorfandflss drawn. aroundffthroug-m the,I pump body, being` scraped `from the rotan-by; a- `non-magnetic tonguefor lscraper securedfto theg-f, pump casing.

Specific Vexamples of apparatusfembodyinthca vari-ousfeatures of therinstantfinyention willnows bez described; in conjunction with'y the accenna@ panyingv draw-ing; wherein-.z

Eig. 1 isfa schematic View, of:affclosed:,hydzlfSallie: system, embodying. the principles of. the:1 instant finvention;

Fig. 2.isa longitudinal 'cross sectionof ,asvalAve.,r forming a..sp ecic featurefof the-instant,in-vex 1.` tion;, Eig. `3 `;is..a cross section otgthe.,valvertakenson; line 3,-3,.of. Fig. 2,.;

` Fig. 5,. of. another. specific;embodimenaot.- ther in Fig. 4, illustrating the interior of the pump mechanism.

Referring to Fig. 1, II designates a closed conduit system, filled with a field-sensitive fluid, for example, a ferro-magnetic fluid. By ferromagnetic fluid, used herein, is meant any fluid which exhibits ferro-magnetic properties so as to change its character when subjected to a magnetic field. An example of such a fluid is a mixture of oil and very finely divided iron particles which hang suspended in the oil so that the entire fluid tends to become somewhat homogeneous.

In the hydraulic system employing the conduit I I, there is placed a suitable fluid pump I2 and a fluid controlling valve I3. The pump is driven through a shaft I4 from any suitable source of power I6. If desired, several pumps and valves may be paralleled, as shown at I2a, I2b, I3a and I3b, respectively, to impart variable capacity to the system. The output from the pump I2 is utilized in a fluid motor I1, which structurally may be identical to the pump I2.

One form of the valve I3 is shown in Fig. 2, wherein a body I8, having a longitudinal passage I9 therethrough, is provided with a magnetic member 2I, shown in the form of a toroidal shell surrounding the passage I9. A ferro-magnetic member 22 is held spaced from the walls of the passage I9 by non-magnetic spacers 23, and thereby forms an annular passageway 26 through the body I8. A winding 24 is embedded in the member 2I surrounding the passageway I9 and the magnetic member 22, to provide means for creating a magnetic field across the annular pors tion 26 of the passageway I9 of selectively controllable strength.

When a ferro-magnetic fluid is caused to now through the passage I9 of the body I8, the extent` i of fluid blocking in the annular passage 26 is dependent upon the magnetic field strength applied across the passage by the winding 24. In this Way, fluid may be allowed to flow virtually unimpeded through the body I8, or may be completely cut off, or any degree of restriction between these limits may be imposed in continuously variable fashion by merely controlling the current in the winding 24.

There is also provided a pump for ferro-magnetic fluid, as shown in Figs. 4 and 5, wherein 3I designates a pump body having a cavity 32 therein. The body 3| is of generally cylindrical shape, and passing concentrically therethrough is rotatably mounted a shaft 33, to which is secured by a key 34 a rotor 35 disposed within the cavity 32. The rotor 35 consists of a pair of identical cup-shaped members 36 and 31, mounted on the shaft 33, and facing each other, so that the facing edges of the members 36 and 31 form therebetween an annular gap 38 at the periphery of the rotor. The rotor 35 also includes a winding 39, disposed within the members 36 and 31 circumjacent the shaft 33, one electrical lead from which is grounded to the shaft as shown at 4 I, the other leadbeing brought out along the axis of the shaft and terminating in a centrally disposed contact button 42, insulated from the shaft proper. A brush 43 bears axially against the contact button 42, and a brush 44 bears against the shaft 33, so that by means of the leads 46 connected to these respective brushes, electric current may be applied to the winding 39 while the shaft 33 is rotating.

The body 3| has a plurality of passages communicating exteriorly thereof, and with the annular gap 38 of the rotor 35. In the embodiment shown in Fig. 4 there are four such passages, each of which includes an inlet and an outlet. For clarity, only one such passage will be described hereinafter, it being understood that the other passages are substantially identical therewith, being positioned in the other three segments of the body 3I aroundthe rotor 35.

Referring to Fig. 4, one of the passages is shown having an inlet 41 and an outlet 48, the intermediate portion 49 of the passage coinciding with the annular gap 38 of the rotor 35, and being bounded f circumferentially by a non-magnetic spacer 5I in which it is formed. The passage 49 is terminated at each end by a non-magnetic tongue or scraper 52, formed integral with the spacer 5I and extending radially inward into the gap 38 as far as the bottom of the gap. The bottom of the gap is formed by a non-magnetic cylinder 53 enclosing the winding 39 and uniting the two halves 36 and 31 of the rotor. The inlet 41 communicates with an annular chamber or passage 54, which also communicates with the inlet portions of each of the other three passages in the body 3l. The outlet passage 48, directed opposite to that of the inlet passages, communicates with a similar annular passage 56, as do the outlet passages of each of the other three fluid passages in the body 3 I. A single threaded inlet hole 51 serves to supply iiuid to the annular inlet chamber or passage 54, and a single threaded outlet passage 58 communicating with the passage 56 serves to discharge iiuid from all of the four passages in the body 3 I In this way the four passages are connected in parallel by means of the respective annular passages 54 and 56.

Operation of pump means are attached to the shaft 33 so as to turnv it in a clockwise direction (Fig. 4). Ferro-magnetic fluid is admitted to the inlet passage 51, from which it feeds directly to each of the four passage inlets 41. Application of electric current to the leads 46 energizes the winding 39, and the resulting magnetic flux in the rotor cup members 36 and 31 creates a magnetic field across the rotor gap 38, which extends around the entire periphery of the rotor, and which is directed parallel to the rotor axis. This field causes the ferro-magnetic fluid, admitted at the inlet 41, to adhere to the rotor 35, so that it is drawn continuously into the gap 36 rand around in a clockwise direction, as seen in Fig. 4. Upon encountering the non-magnetic scraper 52, which lls the entire cross-section of the gap, the iiuid is scraped from the surface of the rotor 35. 'Ihe fluid thus disengaged from the rotorl loses much of its magnetism and is pushed out the outlet 48 by the still magnetized fluid behind it in the passage 49. tinuous flow of ferromagnetic fluid is maintained from the inlet 51 to the outlet 58 of the pump.

The coupling between the rotor 35 and the ferro-magnetic fluid may be varied from zero up to a very tight coupling, by adjusting the current in the winding 39. In this way, without changing the speed of the rotor shaft 33, the output of the pump may be varied from zero up to full' In this Way, a. 6011-.

similar, except that the fluid, instead of being merely admitted to the inlet 51, is forced thereinto under pressure. Adhering to the rotor 35 because of the magnetic field, the fluid drags the rotor around in a clockwise direction until it is scraped from the rotor by the scraper 52, and discharged through the passages 48, 56, and 58, thus causing the shaft 33 to turn. As when used as a pump, this application of the apparatus also has the advantage of controllably variable coupling between the rotor and the fluid merely by varying a small current through the coil 39.

The device thus constitutes a means of controlling the flow or pressure of a ferro-magnetic uid. or, alternatively, if used as a fluid motor, the speed or torque of the motor output by remote control which uses electric power of magnitude very small relative to the power involved in the total operation of the device.

The apparatus thus described has the advantages of simplicity, economy, inherent amplification, and flexibility. Simplicity is achieved by the elimination of valves, closely lapped surfaces, joint gears, and pilot motors. Economy results from the simple construction of the apparatus. The amplification represented by the device is very great; the current supplied to the device represents almost negligible power compared to the power which can be controlled. The flexibility of the device is likewise very broad. It can serve as a pump, a motor, or a brake, virtually without modication, and can serve all three functions alternatively in the same installation.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

A pump for ferro-magnetic uid comprising a FIRTH PIERCE.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 601,957 Gray Apr. 5, 1898 1,047,329 Sundh Dec. 17, 1912 1,069,408 Gaede Aug. 5, 1913 1,674,914 Murray June 26, 1928 '1,975,965 Meyer Oct. 9, 1934 2,276,895 Vosseler et al Mar. 17, 1942 2,279,243 Parsons Apr. 7, 1942 2,405,127 Beach Aug. 6, 1946 2,505,049 Keller Apr. 25, 1950 OTHER REFERENCES The Magnetic Fluid Clutch, in Bureau of Standards Techanical Report 1213, March 30, 1948. Class 192-Mag. Fluid.

Magnetized Iron-Oil Mixes, in Business Week, December 18, 1948, pages 48-50. Class 192-Mag. Fluid.

New Uses for Magnetic Fluids, in Bureau oi' Standards Bulletin, June 19, 1949, pages 74 and 75. Class 192Mag. Fluid. 

